/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.streaming.examples.gcp.pubsub;

import com.google.cloud.pubsub.v1.Publisher;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.ProjectTopicName;
import com.google.pubsub.v1.PubsubMessage;

import java.math.BigInteger;

/**
 * Helper class to send PubSubMessages to a PubSub topic.
 */
class PubSubPublisher {
	private final String projectName;
	private final String topicName;

	PubSubPublisher(String projectName, String topicName) {
		this.projectName = projectName;
		this.topicName = topicName;
	}

	/**
	 * Publish messages with as payload a single integer.
	 * The integers inside the messages start from 0 and increase by one for each message send.
	 * @param amountOfMessages amount of messages to send
	 */
	void publish(int amountOfMessages) {
		Publisher publisher = null;
		try {
			publisher = Publisher.newBuilder(ProjectTopicName.of(projectName, topicName)).build();
			for (int i = 0; i < amountOfMessages; i++) {
				ByteString messageData = ByteString.copyFrom(BigInteger.valueOf(i).toByteArray());
				PubsubMessage message = PubsubMessage.newBuilder().setData(messageData).build();
				publisher.publish(message).get();

				System.out.println("Published message: " + i);
				Thread.sleep(100L);
			}
		} catch (Exception e) {
			throw new RuntimeException(e);
		} finally {
			try {
				if (publisher != null) {
					publisher.shutdown();
				}
			} catch (Exception e) {
			}
		}
	}
}
